People with higher levels of omega-3 fatty acids also had an overall risk of dying that was 27 percent lower, and a risk of dying from heart disease that was 35 percent lower than counterparts who had lower blood levels, said the study.
The research was led by scientists at the Harvard School of Public Health and was published in the Annals of Internal Medicine.
While other studies have demonstrated a link between omega-3 fatty acids and lower risk of heart disease, this research examined records of older people to determine any link between fish-eating and death risk.
Researchers scanned 16 years of data on about 2,700 US adults aged 65 or older. Those considered for the study were not taking fish oil supplements, to eliminate any confusion over the use of supplements or dietary differences.
Those with the highest blood levels of omega-3 fatty acids found mainly in fish like salmon, tuna, halibut, sardines, herring and mackerel, had the lowest risk of dying from any cause, and lived an average of 2.2 years longer than those with low levels.
Researchers identified docosahexaenoic acid (DHA) as most strongly related to lower risk of coronary heart disease death.
Eicosapentaenoic acid (EPA) was strongly linked to lower risk of nonfatal heart attack, and docosapentaenoic acid (DPA) was most strongly associated with lower risk of dying from a stroke.
The findings persisted after researchers adjusted for demographic, lifestyle and diet factors.
"Our findings support the importance of adequate blood omega-3 levels for cardiovascular health, and suggest that later in life these benefits could actually extend the years of remaining life," said lead author Dariush Mozaffarian, associate professor in the Department of Epidemiology at Harvard School of Public Health.
"The biggest bang-for-your-buck is for going from no intake to modest intake, or about two servings of fatty fish per week," said Mozaffarian.